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Tree of Heaven (Ailanthus altissima)

Tree of Heaven (Ailanthus altissima )

Ailanthus altissima Ailanthus altissima

Family: Simaroubaceae


A very fast-growing deciduous tree to about 20 m high, though usually smaller. Bark is smooth and grey. Leaves are very large (up to 1m long) and compound, with many leaflets in opposite pairs. There is a gland located on a small lobe near the base of each leaflet (see close-up photo). When crushed the leaves have an unpleasant smell a bit like peanut butter. New growth is red. Clusters of flowers occur at the branch tips. Each flower is small and white or greenish. Male flowers smell very unpleasant. The seeds are red, large and winged.

Preferred habitat and impacts:
Found in many situations, often around old farms, but the winged seeds can blow considerable distances and the tree can occur in relatively undisturbed bush.
Dense thickets can shade out and replace native vegetation. Bark and leaves are toxic to animals and can cause contact dermatitis in humans.

Winged seeds are spread by wind, but the main means of reproduction is by root suckers. One plant can rapidly become a large thicket. Dumped material may take root. Root fragments can be spread by machinery.

Two similar native trees are red cedar (Toona ciliata) and pencil cedar (Polyscias murrayi ). Both are rainforest trees, and red cedar does not naturally occur south of Milton, though it may be planted outside its natural range. Neither of these trees have the gland on the base of the leaflets, or the unpleasant smell to the crushed leaves. Pencil cedar holds its leaves in a more upright position, and is evergreen. Red cedar is deciduous.
The noxious weed rhus (
Toxicodendron succedaneum) is a similar but smaller tree, with smaller compound leaves which do not have a gland on each leaflet. It is very toxic, especially to susceptible individuals.

Polyscias murrayii Polyscias murrayi pencil cedar Toxicodendron succedaneum Toxicodendron succedaneum Toxicodendron succedaneum

Very young plants can be dug out while they are still small. Larger plants will sucker from the roots when the main plant is cut down or poisoned, and may continue to do so for some years. Repeat treatment is necessary.
Cut and paint, stem injection, basal bark treatment in younger plants, or spray foliage for small plants.
Do not cut trees down without applying herbicide to the stump or massive suckering will result. Ploughing, or slashing of small plants, will have the same effect.